[patch] Added method "getWidgetPosition" for GridContainer

Description

The GridContainerLite? has a new method which can be used to get the position in a column easily.

This is very important when one wants to save the order of widgets in the grid.

It might be left to discuss whether one should return an array a la { column: widget.column, pos: <pos here> }. Because as of now, one needs to call <widget>.column separately to get the column the widget is in.

Ok, after massive triage, ended up with about 80 tickets for 1.11 and 400 or so for 1.12. That's a bit unrealistic, so first I changed all 1.12 to 1.13 (with the plan to move some forward to the new 1.12. Now, I'm moving some of the 1.11 tickets that are less likely to get done this month without help to 1.11. Feel free to help out in January if you want to see this ticket land in 1.11.